Weed Management in Beans Using Subdoses of Fluazifop-P-Butyl + Fomesafen

Abstract

-The objective of this work was to evaluate the effect of reduced doses of the commercial mixture composed of fluazifop-p-butil + fomesafen, applied for the management of common weeds in beans. The experiment was conducted in a completely randomized block design, with a 5x2+1 factorial arrangement and with four replications. In factor A, there were five percentual doses (100, 87.5, 75.0, 62.5 and 0.0%), in relation to the recommended commercial dose (2 L ha -1 ) of fluazifop-pbutil + fomesafen, which corresponded to 2.00; 1.75; 1.50; 1.25 and 0.00 L ha -1. Factor B was composed by two development stages of black beans (three and eight trefoils) and weeds: black-jack (two to four and four to eight leaves) and southern crabgrass (two leaves to one tiller and one to four tillers) with one weeded control treatment. The variables evaluated for the control of black-jack and southern crabgrass were: herbicide phytotoxicity to the crop, number of pods per plant, number of grains per pod, 1,000 grain weight and grain yield of the crop. The results demonstrated that the use of fluazifop-p-butil + fomesafen, at all evaluated doses evaluated and application periods, caused low phytotoxicity to the crop, less than 12%. The use of reduced doses of this herbicide presents efficient control of black-jack and southern crabgrass, mainly at the initial development stages of these weed species. The economic threshold dosage of fluazifop-p-butil + fomesafen to control these weeds was 1.23 L ha

Application of pyraclostrobin as an alternative to reduce phytotoxification of fomesafen in common bean

“…Marchioretto et al (2017) verified low phytotoxicity levels for common bean cultivars ANfc 9, IPR Uirapuru and BRS style at 14 DAA fomesafen (250 g ha -1 ) at the V2 stage. The same was observed by Galon et al (2018) for common bean IPR Tuiuiú with application of fluazifop-p-butyl (250 g ha -1 ) + fomesafen (250 g ha -1 ). The results also corroborate with Cieslik et al (2014) who have recovered phytotoxicity symptoms in common bean plants, cultivars IPR Tiziu and IPR-81 at 21 fomesafen DAA.…”

“…One of the main difficulties for common bean production is due to weed interference (Galon et al 2018), since this shows a low competitive capacity, because it is a plant with reduced ability to shade the soil in the first stages of development. Moreover, its root system is poorly developed and the crop presents a short cycle, making the weed infestation privileged, interfering in the crop and impeding the maximum productive potential from being reached (Cury et al 2011;Manabe et al 2014;Galon et al 2016).…”